Do Patients With ACL Tears Demonstrate Weakness of the Soleus Muscle?

Inclusion Criteria: ACL tear participants: * MRI-confirmed ACL tear. * Participant is willing and able to give informed consent in writing for participation in the study. * Male or Female, aged 18 years to 55 years of age. * No contraindications to strength testing (see exclusion criteria). Normative values from healthy individuals: * No current or previous history of significant lower limb injury, or a history of previous minor injury that is symptomatic at the time of recruitment. * No previous lower limb surgery. * No course of medication, whether prescribed or over the counter, other than vitamins and mineral supplements or, for females, oral contraceptives. Exclusion Criteria: * History of chronic musculoskeletal disease or disorder in either leg that may put the participants at risk because of participation in the study including non-united fractures, epilepsy, cardiac insufficiency, severe peripheral vascular disease, aneurysms, anticoagulant therapy, recent (\<3 months) radiotherapy or chemotherapy, long term steroid use (\>3 months), pregnancy, neurological disorders (e.g., Parkinson's disease), skin conditions at point of force testing, severe osteoporosis, malignancy, rheumatoid arthritis. * Conditions or symptoms that may influence the result of the study, or the participant's ability to participate in the study including pain, limited range of motion, knee effusion, or anaemia.